Book explores how weight loss can hurt running performance

Staff Report

CHAMPAIGN, Ill. — Female runners often correlate weight loss with body fat reduction when attempting to manipulate body composition and enhance performance. But, according to Carolyn Smith, M.D., director of the student health service at Marquette University, and co-author with Jason Karp, Ph.D., of Running for Women (Human Kinetics, 2012), there is little evidence that weight loss results in improved performance in already-lean athletes.

Weight loss in relatively lean female runners is detrimental to their health and can result in a loss of lean body tissue and lead to worsened performance,” Smith said. “Despite negative consequences, the desire to attain the ideal body composition to improve performance is the primary impetus contributing to the development of the female athlete triad in female endurance runners.”

The female athlete triad was first identified as a serious health condition in 1992 and consisted of athletes with disordered eating, menstrual irregularities and osteoporosis. By 2007, more female athletes were at risk of developing the syndrome and the definition was broadened to female athletes experiencing reduced energy, menstrual disorders and low bone mineral density. Each component of the triad is interrelated and exists on a continuum of severity between health and disease.

Progression along the three continuums occurs at different rates, although it is under-fueling (inadequate nutrition) for the level of physical activity that begins the cycle,” Smith said. “Compared with other athletes, female distance runners have a higher incidence of both amenorrhea and reduced energy intake, increasing the likelihood that the triad will be present.”

Runners with components of the triad can perform well for long periods, but eventually the physical and psychological consequences will affect performance and well-being.

As the energy deficit continues, runners will experience a decrease in power, muscle strength and stamina,” Smith said. “Performance gains previously seen from a well-designed training plan will no longer occur, and athletes will have difficulty completing what used to be an effortless workout.”

The most detrimental effect of the triad is continued bone loss leading to irreversible osteoporosis. Thus, resulting stress fractures will be slow to heal because of the negative nutritional balance.

Multiple fractures can lead to increased incidence of osteoarthritis depending on the site of the fractures,” Smith said. “Frequent stress fractures will curtail running activities, and if severe, could permanently end a running career.”

Decreasing weight can improve performance, especially in long races, but Smith warned that modifying body composition must be done in a healthy manner.

Keeping records of body weight, menstrual function and distance run per week will assist runners in finding the ideal body weight for health and performance,” Smith said. “If they have had a stress fracture, find their menstrual cycle has changed, or notice more frequent illnesses or injury, they should seek evaluation by a health care provider.”

For more about Running for Women (paperback, 240 pages, ISBN 978-1-4504-0467-9, $17.95) or other running resources, visit or call 800-747-4457.

From the Aug. 15-21, 2012, issue

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